Insulating housing for electrical apparatus



Dec. 21, 1948. 4 a, a. sP|Ro xflsuuwma 'aousme F013sum-1111mm, APPARATUSFiled Doc. 30, 1944 Inventor:

Benjamin E. Spiro,

H15 Attorney.

Patented Dec. 21, 1948 INSULATING HOUSING FOR ELECTRICAL APPARATUSBenjamin E. Spiro Philadelphia, Pa., assignor to General ElectricCompany, a corporation of New York Application December 20, 1944, SerialNo. 568,984

4 Claims. 1

My invention relates to insulating housings for electrical apparatussuch as electric circuit breakers and more particularly for electric aircircuit breakers of the type disclosed and claimed in Linde Patent2,293,513, granted August 18, 1942, and assigned to the same assignee asthe present application. Specifically my invention is an improvement onBoehne Patent 2,293,452, granted August 18, 1942, and also assigned tothe same assignee as the present application.

As is disclosed and claimed in the above mentioned Boehne patent, aircircuit breakers of the type disclosed in the above mentioned Lindepatent produce large amounts of highly heated arc gases in the shortinterval of time during the circuit interrupting operation. Theexplosive-like generation of incandescent gases by the circuit breakerduring the interrupting operation may cause serious injury and damage toadjacent operators and equipment unless the gases are sumciently cooledto an insulating state before being vented from the arc chute or breakerhousing. The cooling of these gases introduces another problem, i. e.,possible reduction of are interrupting capacity due to excessive backpressure particularly where a compact design is required. In accordancewith the above mentioned Boehne patent the arc chutes of the circuitbreaker are enclosed by a box-barrier arrangement of insulating materialwhich deflects and renders harmless the arc and switching gases blownfrom the are chutes of the circuit breaker while maintaining a highinterrupting capacity of the circuit breaker and a high insulation levelof the complete equipment. The box-barrier construction used heretoforecomprised a plurality of sheetlike members or panels of insulatingmaterial which were arranged in the form of a box and which might bedivided by. a plurality of barriers to isolate thevarious arc chutes ofthe circuit breaker. These box-barriers were usually fastened togetherby a plurality of screws or Other metal fastening means.

It would be desirable to provide a boxbarrier which does not employ anymetal iastenings of any kind which has a greatly increased electricalcreepage path which is more effective from the standpoint ofgasproofness, which has a more pleasing finished appearance, andfurthermore which is less expensive to manufacture.

It is an object of my invention to provide an insulating housing orbox-barrier for gas producing electrical apparatus such as electric aircircuit breakers which has the advantages enumerated above.

It is another object of my invention to provide a new and improvedinsulating housing for the arc chutes of electric circuit breakers.

Further objects and advantages 0! my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

For a better understanding of my invention reference may be had to theaccompanying drawing in which Fig. 1 is an elevational view, partly insection, of an electric circuit breaker embodying my invention; Fig. 2is an end view, partly in section, of Fig. 1; Fig. 3 is an enlargedperspective view of a portion of the insulating housing of Figs. 1 and2; Fig. 4 is an end view of a portion of Fig. 3 prior to assembly as inFig. 3; Fig.'5 is a perspective view of a portion of Fig. 3 illustratingone step in the assembly; Fig. 6 is a sectional view taken on line 6-4of Fig. 3, and Fig. '7 is an enlarged, exploded view of a portion ofFig. 3.

Referring now to the drawing, there is illustrated an electric circuitbreaker substantially identical with the electric circuit breakerdisclosed and claimed in copending application Serial No. 568,983, Spiroet al., filed concurrently with the present application and assigned tothe same assignee as the present application which has matured intoPatent 2,445,190, granted July 13, 1948. The electric circuit breakerillustrated comprises a main supporting frame I, for the movable contactstructure which comprises a relatively fixed contact 2 and a movablecontact 3 which is pivotally mounted at 4 on one end of the circuitbreaker conductor stud 5. The stationary contact 2 is electricallyconnected to a conductor stud 6. Pivotally mounted contact 3 is operatedby means of an operating rod I connected to an actuating mechanism (notshown) preferably carried by the frame I. The conductor studs 5 and 6serve as plug type disconnect contacts for the circuit breaker unit andwhen they are connected to alive power circuit relative separation ofthe contacts of the circuit breaker will cause an arc to be drawn.

For the purpose of interrupting this power arc an arc extinguishingstructure generally indicated at 8 is mounted in the frame i so astoreceive the arc. Suitable means, such as magnetic blow-out coils areprovided to force the arc into the arc chute. Generally such a circuitbreaker comprises a plurality of arc chutes, one for each phaseconductor of the power circuit to be controlled. As illustrated in Fig.2 of the drawing, three are chutes are shown each connected to adifferent set of conductor studs to control the conventional three-phaseelectric circuit. As illustrated in the drawings the arc chutes I are oithe so-called down-draft type such as is disclosed in Linde Patent2,335,068, granted November 23, 1943, and assigned to the same assigneeas the present application. By downdraft type is meant that the arcgases from the arc chute are discharged downwardly. It will beunderstood, however, that my invention is equally applicable to circuitbreakers such as are shown in the above mentioned Boehne patent wherethe arc gases from the arc chute are discharged laterally rather thandownwardly.

The circuit breaker thus far described would probably in the case ofsevere overloads or short circuits eject incandescent gases in varyingamounts. This obviously cannot be tolerated in an indoor station wheresuch breakers are usually employed, as attendants might be seriouslyburned and also damage to other equipment might result in the case offlashover due to the heated gases within the breaker'enclosure which isusually a metal enclosure. In order more completely to house theinterrupting device and guard against injuries or fiashover due topossible ejection oi hot gases, there is provided an insulating housingor box-barrier 9. This housing comprises a front wall or panel ill, atop wall or panel il, a bottom wall or panel I 2, side plates or panelsI: and I4, and a plurality of partitions or interphase barriers l5.These panels are really sheet-like members formed of insulating materialand joined together as a unitary structure in the form of a box-likehousing which is inserted into the position indicated in Figs. 1 and 2and supported by any suitable means, such for example as the lugs IS inFig. 2

extending from the frame I.

In accordance with the disclosure of the above mentioned Boehne patent,the box-barrier 9 receives the gases discharged from the arc chute 8 andpermits these gases to escape to atmosphere through a plurality ofopenings such as H in the bottom wall I! and a plurality of openingssuch as l8 in the front wall 10. By the time these gases are exhaustedto atmosphere through openings l1 and I8 they are sufliciently cooledand by virtue of the box-barrier 9 flashover is prevented since the arcchutes 8 are isolated from each other and the arc gases are preventedfrom impinging against the metallic frame of the circuit breaker untilthey are sufliciently cooled.

Heretofore the box-barriers such as 9 comprised a plurality ofinsulating plates fastened together by suitable metal screws or rivets.The metal screws or rivets greatly increase the probability of flashoverand furthermore the construction was not gas proof at the Joints whichtended to increase the possibility of fiashover.

In accordance with my invention the boxbarrier is constructed withsubstantially no metal parts at all and furthermore the joints aresubstantially gas proof and provide a very long creepage path. Inaddition a much more pleasing construction is presented which is muchless expensive to manufacture.

In accordance with my invention I provide a Junction strip or insulatingmember for Joining two adjacent sheet-like members at a predeterminedangle, which is preferably a right angle. This junction strip or moldingis generally indicated in the drawings as I! and comprises a strip ofinsulating material which is produced by extruding through a special dieof the desired configuration, a suitable plastic material. I have foundthat plastic material such as cellulose esters and particularlyaceto-butyrate is a very desirable extrudable material from which toform the strips or moldings IQ for in addition to being insulating,these materials are tough, hard and resilient and which propertiesaccount for the effectiveness of the corner jointing members for theinsulating housing of my invention. The strips is are produced in theparticular crosssectional configuration clearly indicated in Fig. 4comprising a pair of outer angularly disposed flanges 20 arrangedsomewhat less than right angles with each other, and an innerL-sectioned member 2| intermediate the flanges 20 and integral with saidflanges so as to define a pair of longitudinal grooves or recesses 22for receiving edges of the sheet-lie members or panels such as H), II,l2, l3 and Id. The strips or moldings l9 when initially extruded asshown in Fig. 4, also have the outer flanges 2D curved somewhat inarcuate form. The material is resilient, as already stated, so that whentwo adjacent sheet-like members are assembled in the associated recesses22 the curvature will disappear for the flanges 20 will press sealinglyupon the panel surfaces so as to lie substantially flat thereon as isshown in Figs. 3 and 6 when the panels are opened to their fullpredetermined degree relationship one with the other.

In order to lock the insulating member I! to the sheet-like members orpanels such as III, II, l2, l3 and I4, each of the sheet-like members orpanels is provided with a shallow, longitudinally extending groove23,near to the edge of the panel and parallel to said edge. Theoutwardly extending edges of the flanges 20 of molding l8 preferablyterminate in a longitudinally extending tongue 24 which is adapted tofit into a cooperating groove 23 of an associated panel therebyeffectively providing means for holding the strip [9 securely to thesheet-like member or panel. Because the molding i9 is hard and tough, itserves adequately as the means for effectively joining together twoadjacent panels disposed at a predetermined angle with respect to eachother. It will be obvious that with this arrangement any two adjacentpanels may be prearranged. at said predetermined angle with each otherafter which a joining strip I9 can then he slid endwise into placebetween them with the tongues 24 fitting nicely into the grooves 23. Ihave found, however, that by making the insulating strip 19 fromresilient material, a sheet-like member or panel may be sprung directlyinto the molding, as is clearly shown in Fig. 5 where the sheet-likemember [2 is depicted in the process of being entered laterally into theinsulating strip [9 which latter is already assembled in place on thepanel In. Conversely, the length of joining strip or molding is may besprung directly onto the edge of a panel in preterence to sliding itlengthwise into position on the grooved panels, if desired.

It will be understood from the above description that the four moldingor insulating members joining panels l0 and 13, I0 and l4, l0 and I2,and I0 and II can not slide longitudinally out of position once thebox-barrier is assembled for these four members I9 which form arectangular frame around the front panel iii, are in abutting engagementwith one another at each 01' their ends where they have been cut so asto form mitered corner joints as clearly illustrated not extend outsidethe box barrier.

8 toward the bottom of Figure 2. It is possible, however, for the fourside moldings or insulating strips 18 which join the panels II and I3,II and I4, I! and ii, and i2 and ll to slide longitudinally out ofposition when employing the I tongue and groove method described abovefor only one end of each of these four side moldings is in abuttingengagement at one of the aforementioned mitered corner Joints. Toprevent these last four moldings or insulating members from creepingaway so as to open up these mitered comer joints of the box-barrier, Iprovide additional means for keying these particular moldings intoposition which is best illustrated by Figs. 3 and 6. A small drilledhole 25 is provided in the panel such as I! between the groove 23 andthe edge of the panel. The molding or insulating member I! is thenpermanently deformed by means of a hand punching tool in a mannerindicated at 26 in Fig. 6, so that the extension which projects into thehole or opening 25 prevents any relative sliding movement between themolding i9 and the panels such as M and I3.

The interphase barriers l5 are supported in grooves such as 21 providedin the panels III, II, and ii. In order to lock each of these barriersin position in grooves 21 a single slotted dowel pin 28 best shown inFigs. 3 and 7 may be provided. This dowel pin has a portion of reducedcross section 29 adapted to be inserted in a cooperating opening 30formed in bottom plate i2, as is clearly shown in Fig. 7. The slot inthe dowel pin 28 cooperates with a notch 3| cut into the interphasebarrier 15. This dowel pin may be made of metal if desired since it doesPreferably, however, this dowel pin is also formed oi insulatingmaterial.

In order to assemble the box-barrier 9 the bottom and front panels l2and I0, respectively, could first be joined together by sliding orspringing the molding l9 between them into position. Next the side plateI3 could be put into position while the vertical molding l9 betweenpanels ill and i3 is slid into position. The two interphase barriers iiare then positioned with their lower and side edges in grooves 21 andwith the locking, dowel pins 23 in place as depicted in Figure 3. Thetop panel II can then be placed into position so that its groovescorresponding to 21 in i2 engage the upper edges of interphase barriersIS. The upper horizontal molding i9 between panels ill and Il may thenhe slid into position from the end to which panel 14 is to be connected.The vertical molding l9 between panels l0 and i4 must then be sprungonto front panel i0 after which panel H is then sprung into positioninto this molding. At this stage of the assembly, all panels andbarriers of the box-barrier 9 are properly in place, interlockinglykeyed therein by the inturned flanges 24 of the four moldings is whichlatter now completely enframe the front panel Iii. It will be evidentthat these four moldings constituting the frame around the panel ID arethemselves interlocked effectively and permanently together for they areincapable 01' any end movement due to their abutting relationship at themltered corner joints. The remaining four side moldings which arehorizontally disposed and which join the panels II and i3, i2 and l3, l2and II, and ii and I4 now can he slid lengthwise into position,whereupon the live panels l0, Ii, l2, l3 and I4, the two interphasebarriers it and eight moldings II are all interlocked into a rigid, com

pletely insulated box-like gas prooi struc e. To prevent relativemovement between the ast four horizontal moldings II which wereassembled in the box-barrier 8, these moldings may be deformed by ahand-punching tool so that the depression 26 formed thereby engages withcooperating openings 25 in the panels I! and I4.

From the above discussion it will be obvious that I have provided abox-barrier construction containing no metal members whatever, whichincludes a very long creepage path at the joints for minimizing voltagebreakdown theretrhough, which has a very pleasing appearance and whichis simpler and less expensive to manufacture than constructions usedheretofore. Moreover, the Joints. are substantially gas proof for theresilient flanges 20 press effectively in weatherstrlp fashion upon thesurface of the panels due to the flange curvature and because I havemade the included angle between these flanges less than that between theassociated adjacent panels.

While I have shown and, described a particular embodiment of myinvention, it will be obvious to those skilled in the art that variouschanges and modifications may be made without departing from myinvention in its broader aspects and I, therefore, aim in the appendedclaims to cover all such changes and modifications as fall within thetrue spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An insulating housing for protecting electrical apparatus, saidhousing including a plurality'of insulating side panels maintainedjuxtaposed in predetermined angular relationship, means for conjoiningtogether certain adjacent edges of said panels comprising a junctionstrip of resilient insulating'material which integrally includes a pairof outer flanges angularly disposed relative to one another and an innerL- sectioned member spaced therefrom to define therebetween a pair oflongitudinal recesses in said strip into which said certain adjacentpanel edges are received, the included angle between the flanges of saidflexible strip when free of said panels being less than that maintainedbe tween said adjacent panels so that said flanges press eifectivelyupon the panel surfaces to form a gas seal thereat, and means forlocking said certain panel edges in said recesses includingcooperatingly matching projections and indentations for said panel edgesand said junction strip.

2. An insulating housing for protecting electrical apparatus, saidhousing including a plurality of insulating side panels maintainedjuxtaposed in predetermined angular relationship, means for conjoiningtogether certain adjacent edges of said panels comprising a junctionstrip of resilient insulating material which integrally includes a pairof outer flanges angularly disposed relative to one another and an innerL- sectioned member spaced therefrom to deflne therebetween a pair oflongitudinal recesses in said strip into which said certain adjacentpanel edges are received, the included angle between the flanges of saidflexible strip when free of said panels being less than that'maintainedbetween said adjacent panels so that said flanges press effectively uponthe panel surfaces to form a gas seal thereat,'and means for lockingsaid certain panel edges in said recesses comprising a projectinglongitudinal tongue integral with each said flange and a correspondinggroove cooperating therewith in each said certain panel edge.

3. An insulating housing for protecting electrical apparatus, saidhousing including a plurality of insulating side panels maintainedjuxtaeffectively upon the panel surfaces to form a gas seal thereat, andmeans for locking said certain panel edges in said recesses comprising aprojecting longitudinal tongue integral with each said flange and acorresponding groove cooperating therewith in each said certain paneledge, the said cooperating tongues and grooves constituting the solefastening means for preventing separation between said certain paneledges and said junction strip.

4. An insulating housing for protecting electrical apparatus, saidhousing including a first panel having a plurality of straightperipheral edges and an associated side panel maintained juxtaposedadjacent each said peripheral edge in predetermined angular relationshipwith said first panel, a plurality of junction strips for conjoiningeach said peripheral edge respectively to the edge of its associatedside panel, each strip comprising a length of resilient insulatingmaterial which integrally includes a pair of outer flanges angularlydisposed relative to one another and an inner L-sectioned member spacedtherefrom to define therebetween a pair of Iongitudinal recesses in eachsaid strip into which the associated juxtaposed panel edges arereceived, the included angle between the flanges of each said strip whenfree of said panels being less than that maintained between itsassociated side panel and said first panel, and means for preventingseparation between each said strip and its associated panels comprisinga projecting longitudinal tongue on each said outer flange and acooperating groove near each associated panel edge, each end of eachsaid Junetion strip being mitered and in abutting relationship to an endof its adjoining strip so that said plurality of strips completelyenirame said first panel in interlocking relationship with said panelsand with each other.

BENJAMIN E. SPIRO.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 157,399 Holmes Dec. 1, 1874728,688 Dyarmen May 19, 1903 906,208 Dewey et a1 Dec. 8, 1908 1,719,269Kelle July 2, 1929 2,293,452 Boehne Aug. 18, 1942

